Subjective cognitive decline and stage 2 of Alzheimer disease in patients from memory centers

Abstract Introduction It is uncertain whether subjective cognitive decline (SCD) in individuals who seek medical help serves the identification of the initial symptomatic stage 2 of the Alzheimer's disease (AD) continuum. Methods Cross‐sectional and longitudinal data from the multicenter, memory clinic–based DELCODE study. Results The SCD group showed slightly worse cognition as well as more subtle functional and behavioral symptoms than the control group (CO). SCD–A+ cases (39.3% of all SCD) showed greater hippocampal atrophy, lower cognitive and functional performance, and more behavioral symptoms than CO–A+. Amyloid concentration in the CSF had a greater effect on longitudinal cognitive decline in SCD than in the CO group. Discussion Our data suggests that SCD serves the identification of stage 2 of the AD continuum and that stage 2, operationalized as SCD‐A+, is associated with subtle, but extended impact of AD pathology in terms of neurodegeneration, symptoms and clinical progression.